Thousand to that urgent health alert about the mysterious illness called afm. It often starts like a common cold then leads to paralysis and the CDC is out with new numbers confirming 62 cases across 22 states. Most of them involving children. ABC's Eva pilgrim is here with the details. Good mning, Eva. Reporter: Good morning. The scariest part is how little we know about it. The CDC calling it a mystery, and what we do know, it is paralyzing and seems to be targeting young children. Camden Carr has been in the hospital for weeks. His parents say it started as a sinus infection but quickly escalated leaving him barely able to speak or move. I can't tell you how he feels and how he's hurting or anything. So it's heartbreaking. Reporter: Camden is fighting acute flaccid myelitis or afm, a rail illness with polio-like symptoms that primarily strikes children. After spikes in 2014 and 2016, the CDC says we could be seeing a similar outbreak. This illness affects less than 1 in a million but it's serious so the CDC is urging parents to look for any sudden weakness in the arms or leg. Despite lots of investigation by CDC and its partners we don't know where afm comes from and we don't know what is causing it. Reporter: 7-month-old Zoe buiter was diagnosed three weeks ago. Even though she is doing better doctors haven't said whether she is expected to make a full recovery. She's a lot more mobile. A lot more active. Still, no strength in her arm. We do see a little movement in her fingers sometimes. Reporter: So far this year, 127 patients are under investigation. 62 confirmed cases in 22 states. The average age, 4 years old like Camden whose parents hope his story will help other families. Your kid could just have a cold, but make sure of it. Reporter: And so many questions still this morning. Doctors don't know where it's coming from, how it's transferred or the reason for this recent uptick and at this point there is no cure. There's not even a treatment for it. The way they diagnose it is by process of elimination so a lot of parents waiting and worried. All you can do is do the Normal things to prevent against illness. Exactly. Eva, thanks very much.

This transcript has been automatically generated and may not be 100% accurate.

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